Thermoelectric or Peltier refrigerators produce only a moderate amount of cooling but have poor efficiencies when compared to compressor based refrigerators. The thermoelectric energy conversion efficiency is measured in terms of the dimensionless “figure of merit, ZT”. To maximize ZT, materials with large Seebeck coefficient, high electrical conductivity, but with low thermal conductivity are needed. The known intermetallic compound YbAl3 has a relatively high Seebeck coefficient and high electrical conductivity but its thermal conductivity is too high e.g. 12 W/μK. Usually intermetallic materials are poor thermoelectric materials but this compound exhibits unusual transport properties leading to a large Seebeck coefficient. Adding materials with very low thermal conductivity lowers the ZT, if the addition does not degrade the other inter-related parameters.